package p2p import ( "context" "errors" "fmt" "math" "math/rand" "sort" "sync" "time" "github.com/gogo/protobuf/proto" "github.com/google/orderedcode" dbm "github.com/tendermint/tm-db" tmsync "github.com/tendermint/tendermint/libs/sync" p2pproto "github.com/tendermint/tendermint/proto/tendermint/p2p" ) const ( // retryNever is returned by retryDelay() when retries are disabled. retryNever time.Duration = math.MaxInt64 ) // PeerStatus is a peer status. // // The peer manager has many more internal states for a peer (e.g. dialing, // connected, evicting, and so on), which are tracked separately. PeerStatus is // for external use outside of the peer manager. type PeerStatus string const ( PeerStatusUp PeerStatus = "up" // connected and ready PeerStatusDown PeerStatus = "down" // disconnected PeerStatusGood PeerStatus = "good" // peer observed as good PeerStatusBad PeerStatus = "bad" // peer observed as bad ) // PeerScore is a numeric score assigned to a peer (higher is better). type PeerScore uint8 const ( PeerScorePersistent PeerScore = math.MaxUint8 // persistent peers ) // PeerUpdate is a peer update event sent via PeerUpdates. type PeerUpdate struct { NodeID NodeID Status PeerStatus } // PeerUpdates is a peer update subscription with notifications about peer // events (currently just status changes). type PeerUpdates struct { routerUpdatesCh chan PeerUpdate reactorUpdatesCh chan PeerUpdate closeCh chan struct{} closeOnce sync.Once } // NewPeerUpdates creates a new PeerUpdates subscription. It is primarily for // internal use, callers should typically use PeerManager.Subscribe(). The // subscriber must call Close() when done. func NewPeerUpdates(updatesCh chan PeerUpdate, buf int) *PeerUpdates { return &PeerUpdates{ reactorUpdatesCh: updatesCh, routerUpdatesCh: make(chan PeerUpdate, buf), closeCh: make(chan struct{}), } } // Updates returns a channel for consuming peer updates. func (pu *PeerUpdates) Updates() <-chan PeerUpdate { return pu.reactorUpdatesCh } // SendUpdate pushes information about a peer into the routing layer, // presumably from a peer. func (pu *PeerUpdates) SendUpdate(update PeerUpdate) { select { case <-pu.closeCh: case pu.routerUpdatesCh <- update: } } // Close closes the peer updates subscription. func (pu *PeerUpdates) Close() { pu.closeOnce.Do(func() { // NOTE: We don't close updatesCh since multiple goroutines may be // sending on it. The PeerManager senders will select on closeCh as well // to avoid blocking on a closed subscription. close(pu.closeCh) }) } // Done returns a channel that is closed when the subscription is closed. func (pu *PeerUpdates) Done() <-chan struct{} { return pu.closeCh } // PeerManagerOptions specifies options for a PeerManager. type PeerManagerOptions struct { // PersistentPeers are peers that we want to maintain persistent connections // to. These will be scored higher than other peers, and if // MaxConnectedUpgrade is non-zero any lower-scored peers will be evicted if // necessary to make room for these. PersistentPeers []NodeID // MaxPeers is the maximum number of peers to track information about, i.e. // store in the peer store. When exceeded, the lowest-scored unconnected peers // will be deleted. 0 means no limit. MaxPeers uint16 // MaxConnected is the maximum number of connected peers (inbound and // outbound). 0 means no limit. MaxConnected uint16 // MaxConnectedUpgrade is the maximum number of additional connections to // use for probing any better-scored peers to upgrade to when all connection // slots are full. 0 disables peer upgrading. // // For example, if we are already connected to MaxConnected peers, but we // know or learn about better-scored peers (e.g. configured persistent // peers) that we are not connected too, then we can probe these peers by // using up to MaxConnectedUpgrade connections, and once connected evict the // lowest-scored connected peers. This also works for inbound connections, // i.e. if a higher-scored peer attempts to connect to us, we can accept // the connection and evict a lower-scored peer. MaxConnectedUpgrade uint16 // MinRetryTime is the minimum time to wait between retries. Retry times // double for each retry, up to MaxRetryTime. 0 disables retries. MinRetryTime time.Duration // MaxRetryTime is the maximum time to wait between retries. 0 means // no maximum, in which case the retry time will keep doubling. MaxRetryTime time.Duration // MaxRetryTimePersistent is the maximum time to wait between retries for // peers listed in PersistentPeers. 0 uses MaxRetryTime instead. MaxRetryTimePersistent time.Duration // RetryTimeJitter is the upper bound of a random interval added to // retry times, to avoid thundering herds. 0 disables jitter. RetryTimeJitter time.Duration // PeerScores sets fixed scores for specific peers. It is mainly used // for testing. A score of 0 is ignored. PeerScores map[NodeID]PeerScore // PrivatePeerIDs defines a set of NodeID objects which the PEX reactor will // consider private and never gossip. PrivatePeers map[NodeID]struct{} // persistentPeers provides fast PersistentPeers lookups. It is built // by optimize(). persistentPeers map[NodeID]bool } // Validate validates the options. func (o *PeerManagerOptions) Validate() error { for _, id := range o.PersistentPeers { if err := id.Validate(); err != nil { return fmt.Errorf("invalid PersistentPeer ID %q: %w", id, err) } } for id := range o.PrivatePeers { if err := id.Validate(); err != nil { return fmt.Errorf("invalid private peer ID %q: %w", id, err) } } if o.MaxConnected > 0 && len(o.PersistentPeers) > int(o.MaxConnected) { return fmt.Errorf("number of persistent peers %v can't exceed MaxConnected %v", len(o.PersistentPeers), o.MaxConnected) } if o.MaxPeers > 0 { if o.MaxConnected == 0 || o.MaxConnected+o.MaxConnectedUpgrade > o.MaxPeers { return fmt.Errorf("MaxConnected %v and MaxConnectedUpgrade %v can't exceed MaxPeers %v", // nolint o.MaxConnected, o.MaxConnectedUpgrade, o.MaxPeers) } } if o.MaxRetryTime > 0 { if o.MinRetryTime == 0 { return errors.New("can't set MaxRetryTime without MinRetryTime") } if o.MinRetryTime > o.MaxRetryTime { return fmt.Errorf("MinRetryTime %v is greater than MaxRetryTime %v", // nolint o.MinRetryTime, o.MaxRetryTime) } } if o.MaxRetryTimePersistent > 0 { if o.MinRetryTime == 0 { return errors.New("can't set MaxRetryTimePersistent without MinRetryTime") } if o.MinRetryTime > o.MaxRetryTimePersistent { return fmt.Errorf("MinRetryTime %v is greater than MaxRetryTimePersistent %v", // nolint o.MinRetryTime, o.MaxRetryTimePersistent) } } return nil } // isPersistentPeer checks if a peer is in PersistentPeers. It will panic // if called before optimize(). func (o *PeerManagerOptions) isPersistent(id NodeID) bool { if o.persistentPeers == nil { panic("isPersistentPeer() called before optimize()") } return o.persistentPeers[id] } // optimize optimizes operations by pregenerating lookup structures. It's a // separate method instead of memoizing during calls to avoid dealing with // concurrency and mutex overhead. func (o *PeerManagerOptions) optimize() { o.persistentPeers = make(map[NodeID]bool, len(o.PersistentPeers)) for _, p := range o.PersistentPeers { o.persistentPeers[p] = true } } // PeerManager manages peer lifecycle information, using a peerStore for // underlying storage. Its primary purpose is to determine which peer to connect // to next (including retry timers), make sure a peer only has a single active // connection (either inbound or outbound), and evict peers to make room for // higher-scored peers. It does not manage actual connections (this is handled // by the Router), only the peer lifecycle state. // // For an outbound connection, the flow is as follows: // - DialNext: return a peer address to dial, mark peer as dialing. // - DialFailed: report a dial failure, unmark as dialing. // - Dialed: report a dial success, unmark as dialing and mark as connected // (errors if already connected, e.g. by Accepted). // - Ready: report routing is ready, mark as ready and broadcast PeerStatusUp. // - Disconnected: report peer disconnect, unmark as connected and broadcasts // PeerStatusDown. // // For an inbound connection, the flow is as follows: // - Accepted: report inbound connection success, mark as connected (errors if // already connected, e.g. by Dialed). // - Ready: report routing is ready, mark as ready and broadcast PeerStatusUp. // - Disconnected: report peer disconnect, unmark as connected and broadcasts // PeerStatusDown. // // When evicting peers, either because peers are explicitly scheduled for // eviction or we are connected to too many peers, the flow is as follows: // - EvictNext: if marked evict and connected, unmark evict and mark evicting. // If beyond MaxConnected, pick lowest-scored peer and mark evicting. // - Disconnected: unmark connected, evicting, evict, and broadcast a // PeerStatusDown peer update. // // If all connection slots are full (at MaxConnections), we can use up to // MaxConnectionsUpgrade additional connections to probe any higher-scored // unconnected peers, and if we reach them (or they reach us) we allow the // connection and evict a lower-scored peer. We mark the lower-scored peer as // upgrading[from]=to to make sure no other higher-scored peers can claim the // same one for an upgrade. The flow is as follows: // - Accepted: if upgrade is possible, mark connected and add lower-scored to evict. // - DialNext: if upgrade is possible, mark upgrading[from]=to and dialing. // - DialFailed: unmark upgrading[from]=to and dialing. // - Dialed: unmark upgrading[from]=to and dialing, mark as connected, add // lower-scored to evict. // - EvictNext: pick peer from evict, mark as evicting. // - Disconnected: unmark connected, upgrading[from]=to, evict, evicting. type PeerManager struct { selfID NodeID options PeerManagerOptions rand *rand.Rand dialWaker *tmsync.Waker // wakes up DialNext() on relevant peer changes evictWaker *tmsync.Waker // wakes up EvictNext() on relevant peer changes closeCh chan struct{} // signal channel for Close() closeOnce sync.Once mtx sync.Mutex store *peerStore subscriptions map[*PeerUpdates]*PeerUpdates // keyed by struct identity (address) dialing map[NodeID]bool // peers being dialed (DialNext → Dialed/DialFail) upgrading map[NodeID]NodeID // peers claimed for upgrade (DialNext → Dialed/DialFail) connected map[NodeID]bool // connected peers (Dialed/Accepted → Disconnected) ready map[NodeID]bool // ready peers (Ready → Disconnected) evict map[NodeID]bool // peers scheduled for eviction (Connected → EvictNext) evicting map[NodeID]bool // peers being evicted (EvictNext → Disconnected) } // NewPeerManager creates a new peer manager. func NewPeerManager(selfID NodeID, peerDB dbm.DB, options PeerManagerOptions) (*PeerManager, error) { if selfID == "" { return nil, errors.New("self ID not given") } if err := options.Validate(); err != nil { return nil, err } options.optimize() store, err := newPeerStore(peerDB) if err != nil { return nil, err } peerManager := &PeerManager{ selfID: selfID, options: options, rand: rand.New(rand.NewSource(time.Now().UnixNano())), // nolint:gosec dialWaker: tmsync.NewWaker(), evictWaker: tmsync.NewWaker(), closeCh: make(chan struct{}), store: store, dialing: map[NodeID]bool{}, upgrading: map[NodeID]NodeID{}, connected: map[NodeID]bool{}, ready: map[NodeID]bool{}, evict: map[NodeID]bool{}, evicting: map[NodeID]bool{}, subscriptions: map[*PeerUpdates]*PeerUpdates{}, } if err = peerManager.configurePeers(); err != nil { return nil, err } if err = peerManager.prunePeers(); err != nil { return nil, err } return peerManager, nil } // configurePeers configures peers in the peer store with ephemeral runtime // configuration, e.g. PersistentPeers. It also removes ourself, if we're in the // peer store. The caller must hold the mutex lock. func (m *PeerManager) configurePeers() error { if err := m.store.Delete(m.selfID); err != nil { return err } configure := map[NodeID]bool{} for _, id := range m.options.PersistentPeers { configure[id] = true } for id := range m.options.PeerScores { configure[id] = true } for id := range configure { if peer, ok := m.store.Get(id); ok { if err := m.store.Set(m.configurePeer(peer)); err != nil { return err } } } return nil } // configurePeer configures a peer with ephemeral runtime configuration. func (m *PeerManager) configurePeer(peer peerInfo) peerInfo { peer.Persistent = m.options.isPersistent(peer.ID) peer.FixedScore = m.options.PeerScores[peer.ID] return peer } // newPeerInfo creates a peerInfo for a new peer. func (m *PeerManager) newPeerInfo(id NodeID) peerInfo { peerInfo := peerInfo{ ID: id, AddressInfo: map[NodeAddress]*peerAddressInfo{}, } return m.configurePeer(peerInfo) } // prunePeers removes low-scored peers from the peer store if it contains more // than MaxPeers peers. The caller must hold the mutex lock. func (m *PeerManager) prunePeers() error { if m.options.MaxPeers == 0 || m.store.Size() <= int(m.options.MaxPeers) { return nil } ranked := m.store.Ranked() for i := len(ranked) - 1; i >= 0; i-- { peerID := ranked[i].ID switch { case m.store.Size() <= int(m.options.MaxPeers): break case m.dialing[peerID]: case m.connected[peerID]: default: if err := m.store.Delete(peerID); err != nil { return err } } } return nil } // Add adds a peer to the manager, given as an address. If the peer already // exists, the address is added to it if it isn't already present. This will push // low scoring peers out of the address book if it exceeds the maximum size. func (m *PeerManager) Add(address NodeAddress) (bool, error) { if err := address.Validate(); err != nil { return false, err } if address.NodeID == m.selfID { return false, fmt.Errorf("can't add self (%v) to peer store", m.selfID) } m.mtx.Lock() defer m.mtx.Unlock() peer, ok := m.store.Get(address.NodeID) if !ok { peer = m.newPeerInfo(address.NodeID) } _, ok = peer.AddressInfo[address] // if we already have the peer address, there's no need to continue if ok { return false, nil } // else add the new address peer.AddressInfo[address] = &peerAddressInfo{Address: address} if err := m.store.Set(peer); err != nil { return false, err } if err := m.prunePeers(); err != nil { return true, err } m.dialWaker.Wake() return true, nil } // PeerRatio returns the ratio of peer addresses stored to the maximum size. func (m *PeerManager) PeerRatio() float64 { if m.options.MaxPeers == 0 { return 0 } m.mtx.Lock() defer m.mtx.Unlock() return float64(m.store.Size()) / float64(m.options.MaxPeers) } // DialNext finds an appropriate peer address to dial, and marks it as dialing. // If no peer is found, or all connection slots are full, it blocks until one // becomes available. The caller must call Dialed() or DialFailed() for the // returned peer. func (m *PeerManager) DialNext(ctx context.Context) (NodeAddress, error) { for { address, err := m.TryDialNext() if err != nil || (address != NodeAddress{}) { return address, err } select { case <-m.dialWaker.Sleep(): case <-ctx.Done(): return NodeAddress{}, ctx.Err() } } } // TryDialNext is equivalent to DialNext(), but immediately returns an empty // address if no peers or connection slots are available. func (m *PeerManager) TryDialNext() (NodeAddress, error) { m.mtx.Lock() defer m.mtx.Unlock() // We allow dialing MaxConnected+MaxConnectedUpgrade peers. Including // MaxConnectedUpgrade allows us to probe additional peers that have a // higher score than any other peers, and if successful evict it. if m.options.MaxConnected > 0 && len(m.connected)+len(m.dialing) >= int(m.options.MaxConnected)+int(m.options.MaxConnectedUpgrade) { return NodeAddress{}, nil } for _, peer := range m.store.Ranked() { if m.dialing[peer.ID] || m.connected[peer.ID] { continue } for _, addressInfo := range peer.AddressInfo { if time.Since(addressInfo.LastDialFailure) < m.retryDelay(addressInfo.DialFailures, peer.Persistent) { continue } // We now have an eligible address to dial. If we're full but have // upgrade capacity (as checked above), we find a lower-scored peer // we can replace and mark it as upgrading so noone else claims it. // // If we don't find one, there is no point in trying additional // peers, since they will all have the same or lower score than this // peer (since they're ordered by score via peerStore.Ranked). if m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected) { upgradeFromPeer := m.findUpgradeCandidate(peer.ID, peer.Score()) if upgradeFromPeer == "" { return NodeAddress{}, nil } m.upgrading[upgradeFromPeer] = peer.ID } m.dialing[peer.ID] = true return addressInfo.Address, nil } } return NodeAddress{}, nil } // DialFailed reports a failed dial attempt. This will make the peer available // for dialing again when appropriate (possibly after a retry timeout). // // FIXME: This should probably delete or mark bad addresses/peers after some time. func (m *PeerManager) DialFailed(address NodeAddress) error { m.mtx.Lock() defer m.mtx.Unlock() delete(m.dialing, address.NodeID) for from, to := range m.upgrading { if to == address.NodeID { delete(m.upgrading, from) // Unmark failed upgrade attempt. } } peer, ok := m.store.Get(address.NodeID) if !ok { // Peer may have been removed while dialing, ignore. return nil } addressInfo, ok := peer.AddressInfo[address] if !ok { return nil // Assume the address has been removed, ignore. } addressInfo.LastDialFailure = time.Now().UTC() addressInfo.DialFailures++ if err := m.store.Set(peer); err != nil { return err } // We spawn a goroutine that notifies DialNext() again when the retry // timeout has elapsed, so that we can consider dialing it again. We // calculate the retry delay outside the goroutine, since it must hold // the mutex lock. if d := m.retryDelay(addressInfo.DialFailures, peer.Persistent); d != retryNever { go func() { // Use an explicit timer with deferred cleanup instead of // time.After(), to avoid leaking goroutines on PeerManager.Close(). timer := time.NewTimer(d) defer timer.Stop() select { case <-timer.C: m.dialWaker.Wake() case <-m.closeCh: } }() } m.dialWaker.Wake() return nil } // Dialed marks a peer as successfully dialed. Any further connections will be // rejected, and once disconnected the peer may be dialed again. func (m *PeerManager) Dialed(address NodeAddress) error { m.mtx.Lock() defer m.mtx.Unlock() delete(m.dialing, address.NodeID) var upgradeFromPeer NodeID for from, to := range m.upgrading { if to == address.NodeID { delete(m.upgrading, from) upgradeFromPeer = from // Don't break, just in case this peer was marked as upgrading for // multiple lower-scored peers (shouldn't really happen). } } if address.NodeID == m.selfID { return fmt.Errorf("rejecting connection to self (%v)", address.NodeID) } if m.connected[address.NodeID] { return fmt.Errorf("peer %v is already connected", address.NodeID) } if m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected) { if upgradeFromPeer == "" || len(m.connected) >= int(m.options.MaxConnected)+int(m.options.MaxConnectedUpgrade) { return fmt.Errorf("already connected to maximum number of peers") } } peer, ok := m.store.Get(address.NodeID) if !ok { return fmt.Errorf("peer %q was removed while dialing", address.NodeID) } now := time.Now().UTC() peer.LastConnected = now if addressInfo, ok := peer.AddressInfo[address]; ok { addressInfo.DialFailures = 0 addressInfo.LastDialSuccess = now // If not found, assume address has been removed. } if err := m.store.Set(peer); err != nil { return err } if upgradeFromPeer != "" && m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected) { // Look for an even lower-scored peer that may have appeared since we // started the upgrade. if p, ok := m.store.Get(upgradeFromPeer); ok { if u := m.findUpgradeCandidate(p.ID, p.Score()); u != "" { upgradeFromPeer = u } } m.evict[upgradeFromPeer] = true } m.connected[peer.ID] = true m.evictWaker.Wake() return nil } // Accepted marks an incoming peer connection successfully accepted. If the peer // is already connected or we don't allow additional connections then this will // return an error. // // If full but MaxConnectedUpgrade is non-zero and the incoming peer is // better-scored than any existing peers, then we accept it and evict a // lower-scored peer. // // NOTE: We can't take an address here, since e.g. TCP uses a different port // number for outbound traffic than inbound traffic, so the peer's endpoint // wouldn't necessarily be an appropriate address to dial. // // FIXME: When we accept a connection from a peer, we should register that // peer's address in the peer store so that we can dial it later. In order to do // that, we'll need to get the remote address after all, but as noted above that // can't be the remote endpoint since that will usually have the wrong port // number. func (m *PeerManager) Accepted(peerID NodeID) error { m.mtx.Lock() defer m.mtx.Unlock() if peerID == m.selfID { return fmt.Errorf("rejecting connection from self (%v)", peerID) } if m.connected[peerID] { return fmt.Errorf("peer %q is already connected", peerID) } if m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected)+int(m.options.MaxConnectedUpgrade) { return fmt.Errorf("already connected to maximum number of peers") } peer, ok := m.store.Get(peerID) if !ok { peer = m.newPeerInfo(peerID) } // If all connections slots are full, but we allow upgrades (and we checked // above that we have upgrade capacity), then we can look for a lower-scored // peer to replace and if found accept the connection anyway and evict it. var upgradeFromPeer NodeID if m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected) { upgradeFromPeer = m.findUpgradeCandidate(peer.ID, peer.Score()) if upgradeFromPeer == "" { return fmt.Errorf("already connected to maximum number of peers") } } peer.LastConnected = time.Now().UTC() if err := m.store.Set(peer); err != nil { return err } m.connected[peerID] = true if upgradeFromPeer != "" { m.evict[upgradeFromPeer] = true } m.evictWaker.Wake() return nil } // Ready marks a peer as ready, broadcasting status updates to subscribers. The // peer must already be marked as connected. This is separate from Dialed() and // Accepted() to allow the router to set up its internal queues before reactors // start sending messages. func (m *PeerManager) Ready(peerID NodeID) error { m.mtx.Lock() defer m.mtx.Unlock() if m.connected[peerID] { m.ready[peerID] = true m.broadcast(PeerUpdate{ NodeID: peerID, Status: PeerStatusUp, }) } return nil } // EvictNext returns the next peer to evict (i.e. disconnect). If no evictable // peers are found, the call will block until one becomes available. func (m *PeerManager) EvictNext(ctx context.Context) (NodeID, error) { for { id, err := m.TryEvictNext() if err != nil || id != "" { return id, err } select { case <-m.evictWaker.Sleep(): case <-ctx.Done(): return "", ctx.Err() } } } // TryEvictNext is equivalent to EvictNext, but immediately returns an empty // node ID if no evictable peers are found. func (m *PeerManager) TryEvictNext() (NodeID, error) { m.mtx.Lock() defer m.mtx.Unlock() // If any connected peers are explicitly scheduled for eviction, we return a // random one. for peerID := range m.evict { delete(m.evict, peerID) if m.connected[peerID] && !m.evicting[peerID] { m.evicting[peerID] = true return peerID, nil } } // If we're below capacity, we don't need to evict anything. if m.options.MaxConnected == 0 || len(m.connected)-len(m.evicting) <= int(m.options.MaxConnected) { return "", nil } // If we're above capacity (shouldn't really happen), just pick the // lowest-ranked peer to evict. ranked := m.store.Ranked() for i := len(ranked) - 1; i >= 0; i-- { peer := ranked[i] if m.connected[peer.ID] && !m.evicting[peer.ID] { m.evicting[peer.ID] = true return peer.ID, nil } } return "", nil } // Disconnected unmarks a peer as connected, allowing it to be dialed or // accepted again as appropriate. func (m *PeerManager) Disconnected(peerID NodeID) error { m.mtx.Lock() defer m.mtx.Unlock() ready := m.ready[peerID] delete(m.connected, peerID) delete(m.upgrading, peerID) delete(m.evict, peerID) delete(m.evicting, peerID) delete(m.ready, peerID) if ready { m.broadcast(PeerUpdate{ NodeID: peerID, Status: PeerStatusDown, }) } m.dialWaker.Wake() return nil } // Errored reports a peer error, causing the peer to be evicted if it's // currently connected. // // FIXME: This should probably be replaced with a peer behavior API, see // PeerError comments for more details. // // FIXME: This will cause the peer manager to immediately try to reconnect to // the peer, which is probably not always what we want. func (m *PeerManager) Errored(peerID NodeID, err error) error { m.mtx.Lock() defer m.mtx.Unlock() if m.connected[peerID] { m.evict[peerID] = true } m.evictWaker.Wake() return nil } // Advertise returns a list of peer addresses to advertise to a peer. // // FIXME: This is fairly naïve and only returns the addresses of the // highest-ranked peers. func (m *PeerManager) Advertise(peerID NodeID, limit uint16) []NodeAddress { m.mtx.Lock() defer m.mtx.Unlock() addresses := make([]NodeAddress, 0, limit) for _, peer := range m.store.Ranked() { if peer.ID == peerID { continue } for nodeAddr, addressInfo := range peer.AddressInfo { if len(addresses) >= int(limit) { return addresses } // only add non-private NodeIDs if _, ok := m.options.PrivatePeers[nodeAddr.NodeID]; !ok { addresses = append(addresses, addressInfo.Address) } } } return addresses } // Subscribe subscribes to peer updates. The caller must consume the peer // updates in a timely fashion and close the subscription when done, otherwise // the PeerManager will halt. func (m *PeerManager) Subscribe() *PeerUpdates { // FIXME: We use a size 1 buffer here. When we broadcast a peer update // we have to loop over all of the subscriptions, and we want to avoid // having to block and wait for a context switch before continuing on // to the next subscriptions. This also prevents tail latencies from // compounding. Limiting it to 1 means that the subscribers are still // reasonably in sync. However, this should probably be benchmarked. peerUpdates := NewPeerUpdates(make(chan PeerUpdate, 1), 1) m.Register(peerUpdates) return peerUpdates } // Register allows you to inject a custom PeerUpdate instance into the // PeerManager, rather than relying on the instance constructed by the // Subscribe method, which wraps the functionality of the Register // method. // // The caller must consume the peer updates from this PeerUpdates // instance in a timely fashion and close the subscription when done, // otherwise the PeerManager will halt. func (m *PeerManager) Register(peerUpdates *PeerUpdates) { m.mtx.Lock() m.subscriptions[peerUpdates] = peerUpdates m.mtx.Unlock() go func() { for { select { case <-peerUpdates.closeCh: return case <-m.closeCh: return case pu := <-peerUpdates.routerUpdatesCh: m.processPeerEvent(pu) } } }() go func() { select { case <-peerUpdates.Done(): m.mtx.Lock() delete(m.subscriptions, peerUpdates) m.mtx.Unlock() case <-m.closeCh: } }() } func (m *PeerManager) processPeerEvent(pu PeerUpdate) { m.mtx.Lock() defer m.mtx.Unlock() if _, ok := m.store.peers[pu.NodeID]; !ok { m.store.peers[pu.NodeID] = &peerInfo{} } switch pu.Status { case PeerStatusBad: m.store.peers[pu.NodeID].MutableScore-- case PeerStatusGood: m.store.peers[pu.NodeID].MutableScore++ } } // broadcast broadcasts a peer update to all subscriptions. The caller must // already hold the mutex lock, to make sure updates are sent in the same order // as the PeerManager processes them, but this means subscribers must be // responsive at all times or the entire PeerManager will halt. // // FIXME: Consider using an internal channel to buffer updates while also // maintaining order if this is a problem. func (m *PeerManager) broadcast(peerUpdate PeerUpdate) { for _, sub := range m.subscriptions { // We have to check closeCh separately first, otherwise there's a 50% // chance the second select will send on a closed subscription. select { case <-sub.closeCh: continue default: } select { case sub.reactorUpdatesCh <- peerUpdate: case <-sub.closeCh: } } } // Close closes the peer manager, releasing resources (i.e. goroutines). func (m *PeerManager) Close() { m.closeOnce.Do(func() { close(m.closeCh) }) } // Addresses returns all known addresses for a peer, primarily for testing. // The order is arbitrary. func (m *PeerManager) Addresses(peerID NodeID) []NodeAddress { m.mtx.Lock() defer m.mtx.Unlock() addresses := []NodeAddress{} if peer, ok := m.store.Get(peerID); ok { for _, addressInfo := range peer.AddressInfo { addresses = append(addresses, addressInfo.Address) } } return addresses } // Peers returns all known peers, primarily for testing. The order is arbitrary. func (m *PeerManager) Peers() []NodeID { m.mtx.Lock() defer m.mtx.Unlock() peers := []NodeID{} for _, peer := range m.store.Ranked() { peers = append(peers, peer.ID) } return peers } // Scores returns the peer scores for all known peers, primarily for testing. func (m *PeerManager) Scores() map[NodeID]PeerScore { m.mtx.Lock() defer m.mtx.Unlock() scores := map[NodeID]PeerScore{} for _, peer := range m.store.Ranked() { scores[peer.ID] = peer.Score() } return scores } // Status returns the status for a peer, primarily for testing. func (m *PeerManager) Status(id NodeID) PeerStatus { m.mtx.Lock() defer m.mtx.Unlock() switch { case m.ready[id]: return PeerStatusUp default: return PeerStatusDown } } // findUpgradeCandidate looks for a lower-scored peer that we could evict // to make room for the given peer. Returns an empty ID if none is found. // If the peer is already being upgraded to, we return that same upgrade. // The caller must hold the mutex lock. func (m *PeerManager) findUpgradeCandidate(id NodeID, score PeerScore) NodeID { for from, to := range m.upgrading { if to == id { return from } } ranked := m.store.Ranked() for i := len(ranked) - 1; i >= 0; i-- { candidate := ranked[i] switch { case candidate.Score() >= score: return "" // no further peers can be scored lower, due to sorting case !m.connected[candidate.ID]: case m.evict[candidate.ID]: case m.evicting[candidate.ID]: case m.upgrading[candidate.ID] != "": default: return candidate.ID } } return "" } // retryDelay calculates a dial retry delay using exponential backoff, based on // retry settings in PeerManagerOptions. If retries are disabled (i.e. // MinRetryTime is 0), this returns retryNever (i.e. an infinite retry delay). // The caller must hold the mutex lock (for m.rand which is not thread-safe). func (m *PeerManager) retryDelay(failures uint32, persistent bool) time.Duration { if failures == 0 { return 0 } if m.options.MinRetryTime == 0 { return retryNever } maxDelay := m.options.MaxRetryTime if persistent && m.options.MaxRetryTimePersistent > 0 { maxDelay = m.options.MaxRetryTimePersistent } delay := m.options.MinRetryTime * time.Duration(math.Pow(2, float64(failures-1))) if maxDelay > 0 && delay > maxDelay { delay = maxDelay } if m.options.RetryTimeJitter > 0 { delay += time.Duration(m.rand.Int63n(int64(m.options.RetryTimeJitter))) } return delay } // GetHeight returns a peer's height, as reported via SetHeight, or 0 if the // peer or height is unknown. // // FIXME: This is a temporary workaround to share state between the consensus // and mempool reactors, carried over from the legacy P2P stack. Reactors should // not have dependencies on each other, instead tracking this themselves. func (m *PeerManager) GetHeight(peerID NodeID) int64 { m.mtx.Lock() defer m.mtx.Unlock() peer, _ := m.store.Get(peerID) return peer.Height } // SetHeight stores a peer's height, making it available via GetHeight. // // FIXME: This is a temporary workaround to share state between the consensus // and mempool reactors, carried over from the legacy P2P stack. Reactors should // not have dependencies on each other, instead tracking this themselves. func (m *PeerManager) SetHeight(peerID NodeID, height int64) error { m.mtx.Lock() defer m.mtx.Unlock() peer, ok := m.store.Get(peerID) if !ok { peer = m.newPeerInfo(peerID) } peer.Height = height return m.store.Set(peer) } // peerStore stores information about peers. It is not thread-safe, assuming it // is only used by PeerManager which handles concurrency control. This allows // the manager to execute multiple operations atomically via its own mutex. // // The entire set of peers is kept in memory, for performance. It is loaded // from disk on initialization, and any changes are written back to disk // (without fsync, since we can afford to lose recent writes). type peerStore struct { db dbm.DB peers map[NodeID]*peerInfo ranked []*peerInfo // cache for Ranked(), nil invalidates cache } // newPeerStore creates a new peer store, loading all persisted peers from the // database into memory. func newPeerStore(db dbm.DB) (*peerStore, error) { if db == nil { return nil, errors.New("no database provided") } store := &peerStore{db: db} if err := store.loadPeers(); err != nil { return nil, err } return store, nil } // loadPeers loads all peers from the database into memory. func (s *peerStore) loadPeers() error { peers := map[NodeID]*peerInfo{} start, end := keyPeerInfoRange() iter, err := s.db.Iterator(start, end) if err != nil { return err } defer iter.Close() for ; iter.Valid(); iter.Next() { // FIXME: We may want to tolerate failures here, by simply logging // the errors and ignoring the faulty peer entries. msg := new(p2pproto.PeerInfo) if err := proto.Unmarshal(iter.Value(), msg); err != nil { return fmt.Errorf("invalid peer Protobuf data: %w", err) } peer, err := peerInfoFromProto(msg) if err != nil { return fmt.Errorf("invalid peer data: %w", err) } peers[peer.ID] = peer } if iter.Error() != nil { return iter.Error() } s.peers = peers s.ranked = nil // invalidate cache if populated return nil } // Get fetches a peer. The boolean indicates whether the peer existed or not. // The returned peer info is a copy, and can be mutated at will. func (s *peerStore) Get(id NodeID) (peerInfo, bool) { peer, ok := s.peers[id] return peer.Copy(), ok } // Set stores peer data. The input data will be copied, and can safely be reused // by the caller. func (s *peerStore) Set(peer peerInfo) error { if err := peer.Validate(); err != nil { return err } peer = peer.Copy() // FIXME: We may want to optimize this by avoiding saving to the database // if there haven't been any changes to persisted fields. bz, err := peer.ToProto().Marshal() if err != nil { return err } if err = s.db.Set(keyPeerInfo(peer.ID), bz); err != nil { return err } if current, ok := s.peers[peer.ID]; !ok || current.Score() != peer.Score() { // If the peer is new, or its score changes, we invalidate the Ranked() cache. s.peers[peer.ID] = &peer s.ranked = nil } else { // Otherwise, since s.ranked contains pointers to the old data and we // want those pointers to remain valid with the new data, we have to // update the existing pointer address. *current = peer } return nil } // Delete deletes a peer, or does nothing if it does not exist. func (s *peerStore) Delete(id NodeID) error { if _, ok := s.peers[id]; !ok { return nil } if err := s.db.Delete(keyPeerInfo(id)); err != nil { return err } delete(s.peers, id) s.ranked = nil return nil } // List retrieves all peers in an arbitrary order. The returned data is a copy, // and can be mutated at will. func (s *peerStore) List() []peerInfo { peers := make([]peerInfo, 0, len(s.peers)) for _, peer := range s.peers { peers = append(peers, peer.Copy()) } return peers } // Ranked returns a list of peers ordered by score (better peers first). Peers // with equal scores are returned in an arbitrary order. The returned list must // not be mutated or accessed concurrently by the caller, since it returns // pointers to internal peerStore data for performance. // // Ranked is used to determine both which peers to dial, which ones to evict, // and which ones to delete completely. // // FIXME: For now, we simply maintain a cache in s.ranked which is invalidated // by setting it to nil, but if necessary we should use a better data structure // for this (e.g. a heap or ordered map). // // FIXME: The scoring logic is currently very naïve, see peerInfo.Score(). func (s *peerStore) Ranked() []*peerInfo { if s.ranked != nil { return s.ranked } s.ranked = make([]*peerInfo, 0, len(s.peers)) for _, peer := range s.peers { s.ranked = append(s.ranked, peer) } sort.Slice(s.ranked, func(i, j int) bool { // FIXME: If necessary, consider precomputing scores before sorting, // to reduce the number of Score() calls. return s.ranked[i].Score() > s.ranked[j].Score() }) return s.ranked } // Size returns the number of peers in the peer store. func (s *peerStore) Size() int { return len(s.peers) } // peerInfo contains peer information stored in a peerStore. type peerInfo struct { ID NodeID AddressInfo map[NodeAddress]*peerAddressInfo LastConnected time.Time // These fields are ephemeral, i.e. not persisted to the database. Persistent bool Height int64 FixedScore PeerScore // mainly for tests MutableScore int64 // updated by router } // peerInfoFromProto converts a Protobuf PeerInfo message to a peerInfo, // erroring if the data is invalid. func peerInfoFromProto(msg *p2pproto.PeerInfo) (*peerInfo, error) { p := &peerInfo{ ID: NodeID(msg.ID), AddressInfo: map[NodeAddress]*peerAddressInfo{}, } if msg.LastConnected != nil { p.LastConnected = *msg.LastConnected } for _, a := range msg.AddressInfo { addressInfo, err := peerAddressInfoFromProto(a) if err != nil { return nil, err } p.AddressInfo[addressInfo.Address] = addressInfo } return p, p.Validate() } // ToProto converts the peerInfo to p2pproto.PeerInfo for database storage. The // Protobuf type only contains persisted fields, while ephemeral fields are // discarded. The returned message may contain pointers to original data, since // it is expected to be serialized immediately. func (p *peerInfo) ToProto() *p2pproto.PeerInfo { msg := &p2pproto.PeerInfo{ ID: string(p.ID), LastConnected: &p.LastConnected, } for _, addressInfo := range p.AddressInfo { msg.AddressInfo = append(msg.AddressInfo, addressInfo.ToProto()) } if msg.LastConnected.IsZero() { msg.LastConnected = nil } return msg } // Copy returns a deep copy of the peer info. func (p *peerInfo) Copy() peerInfo { if p == nil { return peerInfo{} } c := *p for i, addressInfo := range c.AddressInfo { addressInfoCopy := addressInfo.Copy() c.AddressInfo[i] = &addressInfoCopy } return c } // Score calculates a score for the peer. Higher-scored peers will be // preferred over lower scores. func (p *peerInfo) Score() PeerScore { if p.FixedScore > 0 { return p.FixedScore } if p.Persistent { return PeerScorePersistent } if p.MutableScore <= 0 { return 0 } if p.MutableScore >= math.MaxUint8 { return PeerScore(math.MaxUint8) } return PeerScore(p.MutableScore) } // Validate validates the peer info. func (p *peerInfo) Validate() error { if p.ID == "" { return errors.New("no peer ID") } return nil } // peerAddressInfo contains information and statistics about a peer address. type peerAddressInfo struct { Address NodeAddress LastDialSuccess time.Time LastDialFailure time.Time DialFailures uint32 // since last successful dial } // peerAddressInfoFromProto converts a Protobuf PeerAddressInfo message // to a peerAddressInfo. func peerAddressInfoFromProto(msg *p2pproto.PeerAddressInfo) (*peerAddressInfo, error) { address, err := ParseNodeAddress(msg.Address) if err != nil { return nil, fmt.Errorf("invalid address %q: %w", address, err) } addressInfo := &peerAddressInfo{ Address: address, DialFailures: msg.DialFailures, } if msg.LastDialSuccess != nil { addressInfo.LastDialSuccess = *msg.LastDialSuccess } if msg.LastDialFailure != nil { addressInfo.LastDialFailure = *msg.LastDialFailure } return addressInfo, addressInfo.Validate() } // ToProto converts the address into to a Protobuf message for serialization. func (a *peerAddressInfo) ToProto() *p2pproto.PeerAddressInfo { msg := &p2pproto.PeerAddressInfo{ Address: a.Address.String(), LastDialSuccess: &a.LastDialSuccess, LastDialFailure: &a.LastDialFailure, DialFailures: a.DialFailures, } if msg.LastDialSuccess.IsZero() { msg.LastDialSuccess = nil } if msg.LastDialFailure.IsZero() { msg.LastDialFailure = nil } return msg } // Copy returns a copy of the address info. func (a *peerAddressInfo) Copy() peerAddressInfo { return *a } // Validate validates the address info. func (a *peerAddressInfo) Validate() error { return a.Address.Validate() } // Database key prefixes. const ( prefixPeerInfo int64 = 1 ) // keyPeerInfo generates a peerInfo database key. func keyPeerInfo(id NodeID) []byte { key, err := orderedcode.Append(nil, prefixPeerInfo, string(id)) if err != nil { panic(err) } return key } // keyPeerInfoRange generates start/end keys for the entire peerInfo key range. func keyPeerInfoRange() ([]byte, []byte) { start, err := orderedcode.Append(nil, prefixPeerInfo, "") if err != nil { panic(err) } end, err := orderedcode.Append(nil, prefixPeerInfo, orderedcode.Infinity) if err != nil { panic(err) } return start, end }